JP5177172B2 - Sheet conveying apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus provided with the sheet conveying apparatus, and more particularly, to a technique for reducing an impact sound that causes discomfort to a user that occurs during recording sheet conveyance accompanying image formation. .

FIG. 14 shows a schematic configuration of a printer 200 as an example of a conventional image forming apparatus. In the conventional printer 200, sheets (recording sheets) S stored in a sheet feeding tray such as the sheet feeding cassette 21 are fed one by one onto the conveyance path 23, and the transfer unit 30 is timed by a timing roller pair 24. Sent to.
The sheet S shown in FIG. 15 is conveyed by being excessively fed by the leading edge of the sheet S being abutted against the stopped timing roller pair 24 so that the sheet S is accurately positioned and fed to the transfer unit 30. A configuration in which a loop (deflection) is formed in the conveyance path as in S1 and the rotation of the timing roller pair 24 is started after the sheet is sufficiently aligned (skew correction), and the sheet conveyance is resumed. Is common. At this time, various impact sounds caused by the paper are generated.

  The impact sound includes an impact sound that is generated when the leading edge of the sheet hits the timing roller pair 24, an impact sound that is generated when the peak portion of the loop hits the guide member 231 of the transport path, and the loop is canceled by restarting the sheet transport. 16 (FIG. 16), there is an impact sound (hereinafter referred to as “happing sound”) generated when the bent portion hits the guide member 232 located inside the loop.

In addition, since the connecting portion from the paper feed tray to the transport path is generally curved, the paper trailing edge jumps due to the stiffness of the paper itself at the moment when the paper trailing edge passes through the pair of paper feeding rollers. There is also an impact sound generated by hitting the guide member.
An image forming apparatus such as a copying machine is installed in an office or the like and is often shared by a plurality of users. Especially for those who work in a seat near the image forming apparatus, Each time the user uses the image forming apparatus, the user is exposed to these impact sounds. Therefore, if the frequency is high, the degree of unpleasant impression of the impact sounds like noise increases, resulting in a decrease in work efficiency. In some cases. In recent years, in order to create a comfortable office environment, there has been a demand for noise reduction of office machines, and noise reduction of these impact sounds has also become an important technical issue. Further, among the impact sounds generated due to the paper during the conveyance of the paper, the knocking sound is relatively loud and the degree of uncomfortable feeling by the user is high, so that quietness is particularly important.

JP-A-8-151143 JP 2003-192180 A

Since the knocking sound is generated when the paper hits the guide member when the loop is released, the guide member inside the loop is first retracted to the position where it does not hit even when the paper is straightened. If it is made from the above, it is considered that no sound is generated.
However, in an image forming apparatus that supports paper of a plurality of sizes, there is usually not only one transport path for transporting paper to the image forming unit, but in the paper feed cassette 21 as in the printer 200 shown in FIG. In addition to a conveyance path (hereinafter referred to as “cassette conveyance path”) for conveying the accommodated paper S, there is a conveyance path (hereinafter referred to as “manual conveyance path”) through which the paper is conveyed from the manual feed tray 25. . Since the manual feed tray 25 is generally disposed on the side surface of the main body of the image forming apparatus, the paper conveyance direction in the cassette conveyance path and the paper conveyance direction in the manual conveyance path merge from directions facing each other and the timing roller pair 24. It becomes the composition which leads to.

  In this case, as indicated by a broken line C in FIG. 16, the guide member 232 inside the loop of one conveyance path (the cassette conveyance path in FIG. 16) is positioned and shaped so that it does not come into contact with the straightly extended sheet. The leading edge of the paper (indicated by the broken line S2 in FIG. 16) conveyed from the other conveyance path (the manual feed path in FIG. 16) is the broken line C in FIG. There is a problem that the angle when hitting the guide member shown by (2) becomes large and the sheet is not properly guided to the timing roller pair 24.

  An object of the present invention has been made in view of the above circumstances, and is a sheet conveying apparatus provided with a mechanism that suppresses a knocking sound generated in association with sheet conveyance in a conveyance path in a shape where two opposed conveyance paths merge. And an image forming apparatus provided with the sheet conveying apparatus.

In order to achieve the above object, a fixing device according to the present invention is a set of a first conveying unit that conveys a sheet by a pair of rotating members, one rotating member, and one pressing member pressed by the rotating member. Each of which is provided with second and third conveying means for selectively conveying the sheet to the first conveying means, and the sheet is temporarily transferred between the first conveying means and the second conveying means during the conveyance. A sheet conveying apparatus having a configuration for automatically forming a loop, wherein a position of the loop of the first conveying path from the second conveying means to the first conveying means is at one side A curved portion bent in the protruding direction, including a curved portion bent in the direction in which the sheet is bent by the formation of the loop, and the second conveyance from the third conveyance unit to the first conveyance unit The road is a protrusion of the music part at the music part. An inner guide member including the inner portion of the curved portion of the guide members that merge with the first conveyance path from the side that forms the first conveyance path is used as the third conveyance means. Displaceable between a first position for guiding the sheet conveyed by the first conveying means to a first position and a second position which is a position retracted inward of the curved portion from the first position. A supporting guide displacement mechanism is provided.

With the above configuration, the inner guide member can be displaced between the first position and the second position as necessary. In order to suppress the knocking sound caused by the sheet conveyed from the second conveying means, The inner guide member can be moved back to the second position and moved to the first position to guide the sheet conveyed by the third conveying means to the first conveying means.
The guide displacement mechanism may be configured such that when the sheet is conveyed from the third conveying unit, the inner guide member is moved to the first position and the sheet is conveyed from the second conveying unit. May include moving means for moving to the second position.

Accordingly, the inner guide member can be selectively positioned at the first position and the second position using the moving means according to the sheet conveying means to which the sheet is conveyed, and is conveyed by the third conveying means. It is possible to achieve both proper guidance of the sheet to the first conveying means and suppression of the beating sound caused by the sheet conveyed by the second conveying means.
Here, the inner guide member may be pivotally supported by the apparatus main body frame so as to be displaceable between the first position and the second position.

Thereby, an inner side guide member can be displaced by a sway.
Here, the guide displacement mechanism may include an elastic member, and the inner guide member may be urged by the elastic member in a direction to be displaced from the second position to the first position. .
Thus, when the sheet is conveyed from the second conveying means, the elastic member absorbs the impact when the sheet strikes the inner guide member and suppresses the knocking sound. When the applied pressing force is released, the elastic member returns to the first position due to the urging force of the elastic member. Therefore, when the sheet is conveyed from the third conveying unit, the sheet is transferred to the first conveying unit. Can be guided.

  Further, here, there is further provided a configuration in which a loop is temporarily formed on the sheet between the first conveying means and the third conveying means in the middle of the conveyance, and the first curved line is provided in the second conveyance path. Another curved portion that is bent in a direction protruding toward the portion is included, and among the guide members that form the second transport path, another inner guide member that includes an inner portion of the another curved portion, A third position that guides the sheet conveyed by the second conveying means to the first conveying means, and a position that is retracted inward of the other curved portion from the third position. There may be provided another guide displacement mechanism that is displaceably supported at this position.

Thereby, since another inner guide member can be displaced between the third position and the fourth position as necessary, in order to suppress the knocking sound caused by the sheet conveyed from the third conveying means. The other inner guide member can be moved back to the fourth position, and can be moved to the fourth position to guide the sheet conveyed by the second conveying means to the first conveying means. .
Here, when the sheet is conveyed from the second conveying means, the another guide displacement mechanism moves the other inner guide member to the third position, and the sheet conveys the third conveyance. When transported from the means, another moving means for moving to the fourth position may be included.

Thereby, according to the sheet conveyance means to which the sheet is conveyed, another inner guide member can be selectively positioned at the third position and the fourth position using another movement means, and the second conveyance Appropriate guidance of the sheet conveyed by the means to the first conveying means and suppression of the knocking sound by the sheet conveyed by the third conveying means can both be achieved.
Here, the other inner guide member may be pivotally supported on the apparatus main body frame so as to be displaceable between the third position and the fourth position.

As a result, the other inner guide member can be displaced by swinging.
Further, here, the another guide displacement mechanism includes another elastic member, and the other inner guide member is displaced from the fourth position to the third position by the another elastic member. May be energized.
Thereby, when the sheet is conveyed from the third conveying means, the impact when the sheet hits another inner guide member is absorbed by another elastic member to suppress the knocking sound, and the sheet is When the pressing force applied from the sheet is released, the urging force of another elastic member is received and the sheet returns to the third position. Therefore, when the sheet is conveyed from the second conveying means. Can guide the sheet to the first conveying means.

  Here, the present invention can provide the same effect as an image forming apparatus including the above-described sheet conveying apparatus.

1 is a diagram showing a schematic configuration of an image forming apparatus according to Embodiment 1 of the present invention. 2 is a block diagram illustrating a configuration of a control unit of the image forming apparatus according to Embodiment 1 of the present invention. FIG. In Embodiment 1 of this invention, it is a partially expanded schematic block diagram which shows the position of the cam in the case of feeding from a paper feed cassette. It is a perspective view which shows schematic structure of the guide member, cam, and guide motor which concern on Embodiment 1 of this invention when it sees from the direction of arrow D of FIG. In Embodiment 1 of this invention, it is a partially expanded schematic block diagram which shows the position of the cam in the case of feeding from a manual feed tray. 4 is a flowchart showing the content of a paper transport guide position control process in Embodiment 1 of the present invention. FIG. 6 is a partially enlarged cross-sectional view showing a schematic configuration of a transport path from a paper feed port and a manual feed tray to a secondary transfer position of a paper feed cassette according to Embodiment 2 of the present invention, on a sheet transported from the paper feed cassette; It is a schematic sectional drawing which shows the state in which the loop is formed. FIG. 9 is a partially enlarged cross-sectional view showing a schematic configuration of a transport path from a paper feed port and a manual feed tray to a secondary transfer position in a paper feed cassette according to Embodiment 2 of the present invention. It is a schematic sectional drawing which shows the state by which the loop was eliminated. FIG. 9 is a partially enlarged cross-sectional view illustrating a schematic configuration of a transport path from a paper feed port and a manual feed tray to a secondary transfer position in a paper feed cassette according to Embodiment 2 of the present invention, and is a front end of a paper transported from the manual feed tray It is a schematic sectional drawing which shows the state which contacted the guide member. FIG. 9 is a partially enlarged cross-sectional view showing a schematic configuration of a conveyance path from a paper feed port and a manual feed tray to a secondary transfer position in a paper feed cassette according to Embodiment 3 of the present invention, and is a diagram illustrating a sheet conveyed from the paper feed cassette; It is a schematic sectional drawing which shows the state in which the loop is formed. FIG. 10 is a partially enlarged cross-sectional view showing a schematic configuration of a transport path from a paper feed port and a manual feed tray to a secondary transfer position of a paper feed cassette according to Embodiment 3 of the present invention. It is a schematic sectional drawing which shows the state by which the loop was eliminated. FIG. 9 is a partially enlarged cross-sectional view showing a schematic configuration of a conveyance path from a paper feed port and a manual feed tray to a secondary transfer position in a paper feed cassette according to Embodiment 3 of the present invention, and is a front end of a paper conveyed from the manual feed tray It is a schematic sectional drawing which shows the state which contacted the guide member. It is a flowchart which shows the content of the paper conveyance guide member position control process in the modification 1 of this invention. It is a figure which shows schematic structure of the conventional image forming apparatus. FIG. 9 is a partially enlarged cross-sectional view illustrating a schematic configuration of a conveyance path from a sheet feeding port and a manual feed tray of a conventional image forming apparatus to a secondary transfer position, in which a loop is formed on a sheet conveyed from the sheet feeding cassette; It is a schematic sectional drawing which shows the state formed. FIG. 9 is a partially enlarged cross-sectional view showing a schematic configuration of a transport path from a paper feed port and a manual feed tray of a conventional image forming apparatus to a secondary transfer position, in which a loop of paper transported from the paper feed cassette is It is a schematic sectional drawing which shows the state canceled.

<Embodiment 1>
Hereinafter, embodiments of a fixing device and an image forming apparatus according to the present invention will be described using a tandem color digital printer (hereinafter simply referred to as “printer”) as an example.
(1-1. Overall Configuration of Printer)
FIG. 1 is a schematic cross-sectional view showing the overall configuration of a printer 100 according to an embodiment of the present invention. The printer 100 includes an image forming unit 10, a paper feeding unit 20, a transfer unit 30, a fixing device 40, a control unit 50, and the like.

When this printer 100 is connected to a network (for example, LAN: Local Area Network) and receives an instruction to execute a print job from an external terminal device (not shown), cyan, magenta, yellow, and black are received based on the instruction. The toner images of the respective colors are formed, and these are multiplex-transferred to form a full-color image.
Hereinafter, the reproduction colors of cyan, magenta, yellow, and black are represented as C, M, Y, and K, and the C, M, Y, and K are added as subscripts to the numbers of the components related to the reproduction colors.

The image forming unit 10 includes image forming units 1C, 1M, 1Y, 1K, an optical unit 15, an intermediate transfer belt 31, a cleaner blade 14, and the like.
The transfer unit 30 includes an intermediate transfer belt 31, a drive roller 32, a driven roller 33, a primary transfer roller 34, a cleaner blade 37, and the like.
The intermediate transfer belt 31 is an endless belt, is stretched around a driving roller 32 and a driven roller 33, and is driven around.

The cleaner blades 14 and 37 are disposed in contact with the photosensitive drum 11 and the intermediate transfer belt 31 in the counter direction, respectively, and residual toner, paper dust, and the like on the surfaces of the photosensitive drum 11 and the intermediate transfer belt 31 are arranged. Clean up trash.
The optical unit 15 includes a light emitting element such as a laser diode. The optical unit 15 emits laser light L1 for forming images of C to K colors according to a drive signal from the control unit 50, and exposes and scans the photosensitive drums 11C to 11K. By this exposure scanning, electrostatic latent images are formed on the photosensitive drums 11C to 11K respectively charged by the chargers 12C to 12K. Each electrostatic latent image is formed by the developing units 13C to 13K, and the C to K color toner images are superimposed on the same positions on the intermediate transfer belt 31 on the photosensitive drums 11C to 11K. It is executed at different timings so as to be transferred. Then, the electrostatic images applied by the primary transfer rollers 34 </ b> C to 34 </ b> K sequentially transfer the toner images of the respective colors onto the intermediate transfer belt 31 to form a full-color toner image, and further move toward the secondary transfer position 36.

  On the other hand, the paper supply unit 20 includes a paper supply cassette 21 (first sheet storage unit) that stores the paper S, and a feed roller 22 that feeds the paper S in the paper supply cassette 21 one by one onto the conveyance path 29. A cassette feeding unit 220 (second conveying unit) including the separation roller 26, a manual feed tray 25 (second sheet storage unit) that is attached to a side surface of the main body of the printer 100 and stores the paper S, and a manual tray 25 The manual sheet feeding section 270 (third conveying means) composed of the feeding roller 27 and the separating roller 28 that feeds the sheet S in the conveying path 29 one by one, and the sheet S fed out on the conveying path 29 by 2 A timing roller pair 24 (first conveying means) for taking the timing to send the toner to the next transfer position 36 is provided, and these low rollers are matched with the movement timing of the toner image on the intermediate transfer belt 31. And the sheet S is fed from the sheet feeding unit 20 to the secondary transfer position 36, and the toner image on the intermediate transfer belt 31 is collectively collected on the sheet S by the action of electrostatic force by the secondary transfer roller 35. Secondary transfer is performed. The conveyance path 29 includes a cassette conveyance path 29a (first conveyance path) from the cassette feeding unit 220 to the timing roller pair 24, and a manual conveyance path 29b (first conveyance path) from the manual feeding unit 270 to the timing roller pair 24. 2), and the cassette conveyance path 29a and the manual conveyance path 29b are joined while curving in directions protruding opposite to each other.

The sheet S that has passed through the secondary transfer position 36 is further conveyed to the fixing device 40, and after the toner image (unfixed image) on the sheet S is fixed on the sheet S by heating and pressing in the fixing device 40, The paper is discharged onto the discharge tray 62 via the discharge roller pair 61.
Note that the rolling rollers 26 and 28 are not limited to a rotating body such as a roller, and may be, for example, a fixed type rolling pad.

In addition, the control unit 50 executes communication with an external terminal, image processing, drive control of the above-described units, and the like.
An operation panel 8 (see FIG. 2) is provided at an easy-to-operate position on the upper front surface of the printer 100. On the operation panel 8, in addition to a numeric keypad for inputting the number of copies, a copy start key for instructing the start of copying, and a key for selecting an image forming mode, the status of the printer 100, for example, a job execution instruction is displayed. It has a touch panel type LCD that displays a message screen indicating that it is in a waiting state (standby), etc., and the touch panel function of the LCD displays the paper tray selection and copy density. We accept adjustments.
(1-2. Configuration of the control unit 50)
FIG. 2 is a block diagram illustrating a configuration of the control unit 50.

As shown in the figure, the control unit 50 includes a CPU (Central Processing Unit) 51, a communication interface (I / F) unit 52, a ROM (Read Only Memory) 53, and a RAM (Random Access Memory) 54 as main components. Etc.
The communication I / F unit 52 is an interface for connecting to a LAN (Local Area Network) such as a LAN card or a LAN board, and receives print job data from the outside.

The RAM 54 serves as a work area for the CPU 51.
The CPU 51 reads a necessary program from the ROM 53, and controls the operations of the image forming unit 10, the paper feeding unit 20, the transfer unit 30, and the fixing device 40 in a unified manner with timing, and is received by the communication I / F unit 52. A print job based on the print job data is executed.
The paper feed tray determination unit 511 is a part of the function of the CPU 51. A paper feed tray determination unit 511 determines a paper feed tray that contains sheets used in a print job received by the communication I / F unit 52 and a print job input by the user on the operation panel 8. Based on this, the guide motor 72 is driven to rotate the cam 71. Details will be described later.
(1-3. When paper is fed from the paper cassette)
FIG. 3 is a diagram showing a schematic configuration of the transport path 29 when paper is fed from the paper feed cassette 21.

  The sheets S are sent one by one from the bundle of sheets S stored in the sheet feeding cassette 21 to the transport path 29 by the cassette feeding unit 220. The sheet S sent out from the sheet feeding cassette 21 to the conveyance path 29 is guided to the timing roller pair 24 by the guide members 291 and 292 constituting the guide surface of the conveyance path 29 as indicated by an arrow E1 in the figure. The As shown in the figure, the cassette transport path 29a is curved in a direction protruding in one direction (the right side in the figure in the figure). Then, in the curved portion (curved portion), as in the case of the conventional printer 200 (see FIG. 14), after the loop is formed on the paper S and the skew is corrected, the paper S is fed by the timing roller pair 24. It is conveyed to the next transfer position 36.

  FIG. 4 is a diagram showing a schematic configuration of the guide member 293 (inner guide member) and the cam 71 as seen from the direction of the arrow D in FIG. For the sake of clarity, the guide members 291 and 292, the timing roller pair 24, the feeding roller 22, and the separating roller 26 are not shown here. As shown in the figure, among the guide members that constitute the guide surface that guides the paper S in the transport path 29, the guide member 293 that constitutes the inside of the curve is made of a plate-like metal, resin, or the like, and its timing. A swing support portion 294 provided on the surface opposite to the conveying path near the roller pair side end is pivotally supported by the frame of the apparatus main body around the support shaft 295. In the state shown in FIGS. 3 and 4, the guide member 293 moves farther outward (conveying path side) around the support shaft 295 due to its own weight (right side in FIG. 3, front side in FIG. 4). The cam 71 is in contact with the outer side of the sheet conveyance area of the surface of the guide member 293 on the conveyance path side, and locks the sway. The cam 71 is an eccentric cam having an elliptical cross section by a plane orthogonal to the rotation shaft 73, and is connected to the guide motor 72 by the rotation shaft 73. A paper feed tray determination unit 511 (see FIG. 2), which is a part of the function of the CPU 51, determines a paper feed tray in which the paper S used for the print job is stored, and the CPU 51 controls the guide motor 72 according to the determination result. To drive. The guide motor 72 is, for example, a stepping motor, and is controlled by the CPU 51 to rotate the cam 71 to a predetermined rotation position and move the guide member 293 to a predetermined position. The cam 71, the guide motor 72, the rotation shaft 73, and the CPU 51 constitute a moving unit 70 that moves the guide member 293. The moving portion 70, the swing support portion 294, and the support shaft 295 constitute a guide displacement mechanism that supports the guide member 293 so as to be displaceable and moves the guide member 293 to a predetermined position. In FIG. 4, the CPU 51 is not shown. In addition to the function as a moving means for moving the guide member 293, the cam 71 also has a function as a swing stopper for the guide member 293, and the cam 71 rotates and comes into contact with the guide member 293 at different rotation angles. Thus, the guide member 293 is moved to a different position and locked.

After the skew correction is performed, when the sheet S is started to be transported again by the timing roller pair 24, the loop is canceled and the sheet S is stretched. At this time, the farthest portion 711 farthest from the rotation shaft 73 on the circumferential surface of the cam 71 is in contact with and locked with the guide member 293, and the guide member 293 is connected to the timing roller pair 24 indicated by a broken line C in FIG. Inside the curve from the straight line connecting the cassette feeding unit 220 (the position of the sheet S when the sheet S is transported straightly between the timing roller pair 24 and the cassette feeding unit 220) (The rotation position of the cam 71 at this time is referred to as a “distant position”, and the position of the guide member 293 is referred to as a “retraction position” (second position).) . Thereby, since the paper S does not hit the guide member 293, the hitting sound is suppressed.
(1-4. When paper is fed from the manual feed tray)
FIG. 5 shows a schematic configuration of the transport path 29 when paper is fed from the manual feed tray 25.

  The sheets S are sent out one by one from the bundle (not shown) of sheets S placed on the manual feed tray 25 to the transport path 29 by the manual feeding unit 270. The sheet S sent out from the manual feed tray 25 to the conveyance path 29 is guided to the timing roller pair 24 by the guide member 293 as shown by an arrow E2 in FIG. At this time, as shown in the figure, the cam 71 is in contact with the guide member 293 at the nearest portion 712 (see FIG. 4) closest to the rotation shaft 73 on the peripheral surface of the cam 71, whereby the guide member 293 is 3 is locked at a position farther in the outward direction of the curve than in the case shown in FIG. 3 (the rotation position of the cam 71 at this time is referred to as “proximity position”, and the position of the guide member 293 is referred to as “guide position” ( First position)). As indicated by an arrow E2 in the figure, the manual feed path 29b has a shape curved in a direction protruding in one direction (lower left in the figure in the figure), so that the paper fed from the manual feed unit 270 The leading end of S approaches the guide member 293 at a predetermined angle. At this time, the approaching angle between the guide member 293 and the leading end of the sheet S is such that the sheet S is smoothly guided to the timing roller pair 24. The angle is sufficiently small.

  Note that the lowest position of the swing due to the weight of the guide member 293 (the position of the guide member 293 when the guide member 293 is supported in a stationary state without being locked to anything) may be set as the guide position. However, it is more preferable that the guide position is inward of the curve with respect to the lowest point. In this way, even when the guide member 293 is in the guide position, the guide member 293 receives a force in a direction in which the guide member 293 is pressed against the cam 71 by its own weight, so that the pendulum is moved when the guide member 293 is moved by rotation of the cam 71. The occurrence of unnecessary noise due to repeated contact and separation between the cam 71 and the guide member 293 due to such swinging back can be prevented.

In the above description, the retracted position is the position retracted inward of the curve from the broken line C (see FIG. 3). However, the present invention is not limited to this. For example, even if the position is not retracted to the broken line C but is retracted inwardly of the curve from the guide position, the sheet will absorb a certain amount of force when the paper strikes the guide member when the loop is released. Sound can be suppressed.
(1-5. Guide member position control)
FIG. 6 is a flowchart showing the contents of the guide member position control process in the present embodiment.

  Note that there is a separate main routine (not shown) for controlling the entire printer 100, and is executed each time the subroutine for the guide member position control process is called in the main routine. The subroutine of the guide member position control process is executed when the user presses the start button on the operation panel 8 (see FIG. 2) of the printer 100 or a PC connected to the printer 100 via a network such as a LAN. Called when a user issues a print job from an external terminal. Hereinafter, the same applies to the modification example (1).

  First, when a print job is received, it is determined whether or not the paper S used for the next received print job is stored in the manual feed tray 25 (step S1: YES, step S2). This determination is made by reading the header information of the print job data received by the communication I / F unit 52 by the paper feed tray determination unit 511 (see FIG. 2) or on the operation panel 8 by the user. This is done by accepting a paper feed tray selection input. Hereinafter, the determination of the paper feed tray is performed in the same manner.

In the case of the manual feed tray 25, the guide motor 72 is driven to rotate, the cam 71 is rotated to the close position, the guide member 293 is moved to the guide position, and then the print job is executed (step S2: YES, step S3, Step S4).
If it is not the manual feed tray 25, a print job is executed (step S2: NO, step S4).
Subsequently, it is determined whether or not the print job is completed. If the print job has not ended, the print job is continuously executed (step S5: NO, step S4). If the print job has been completed, it is next determined whether or not the cam 71 is in the distant position (step S5: YES, step S6).

When the cam 71 is not in the distant position, the guide motor 72 is rotationally driven to rotate the cam 71 to the distant position, and the guide member 293 is moved to the retracted position (step S6: NO, step S7), and the main routine Return to If the cam 71 is at the distant position (step S6: YES), the process returns to the main routine.
As described above, when paper is fed from the paper feed cassette 21 during execution of a print job, the guide member 293 is positioned at the retracted position, and when paper is fed from the manual feed tray 25, the guide member By positioning 293 at the guide position, it is possible to suppress paper noise when paper is fed from the paper feed cassette 21 and to properly carry paper even when paper is fed from the manual feed tray 25. Can do.

Further, in normal use of the printer, it is considered that there are few cases where paper is fed from the manual feed tray 25 as compared with the case where paper is fed from the paper feed cassette 21, and therefore, when the print job is completed as in the present embodiment. It is determined whether or not the cam 71 is in the distant position. If the cam 71 is not in the distant position, the cam 71 is rotated to the distant position. Since the member 293 is located at the retracted position, it is not necessary to rotate the cam 71 and move the guide member 293 every time paper is fed from the paper feed cassette 21, and noise is generated when the guide motor 72 is driven to rotate. And power consumption can be reduced.
<Embodiment 2>
In the first embodiment, the configuration has been described in which the guide member 293 is moved by the cam 71 to be positioned at the retracted position and the guide position, and both the suppression of the knocking sound and the appropriate sheet conveyance are realized. In the present embodiment, a configuration that realizes appropriate paper conveyance while absorbing impact when the paper strikes the guide member 293 by the elastic member and suppressing the knocking sound will be described.

In addition, in order to avoid duplication of description, about the same component as Embodiment 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
7, 8, and 9 are diagrams illustrating a schematic configuration of the conveyance path 29 in the present embodiment, and FIG. 7 illustrates a state in which a loop is formed on the sheet fed from the sheet feeding cassette 21. FIG. 8 shows a state when the loop of FIG. 7 is eliminated, and FIG. 9 shows a state where the leading edge of the paper fed from the manual feed tray 25 hits the guide member 293.

One end of the compression spring 81 (first elastic member) is connected to the surface of the guide member 293 opposite to the conveyance path 29, and the other end of the compression spring 81 is the frame of the printer 100 main body. It is being fixed to fixing members 82, such as.
8 and 9, the positions of the guide member 293 and the compression spring 81 in FIG. 7 are indicated by broken lines.

  When the state shown in FIG. 7 shifts from the state in which the loop is formed on the paper to the state in which the loop is eliminated as shown in FIG. 8, the guide member 293 receives a pressing force in the curved inward direction from the paper. Then, the compression spring 81 is compressed by the pressing force, and the guide member 293 swings in the inner side of the curve and moves to the retracted position shown in FIG. At this time, since the pressing force is absorbed by the compression spring 81, the force with which the sheet strikes the guide member 293 is weakened, and as a result, the beating sound is suppressed. When the trailing edge of the sheet passes through the cassette feeding unit 220 (the nip portion between the feeding roller 22 and the separating roller 26), the pressing force disappears, and the guide member 293 is moved to the position shown in FIG. Is returned to.

  When the paper is fed from the manual feed tray 25, when the paper S sent from the manual feeding unit 270 into the transport path 29 is transported to the timing roller pair 24, the leading edge of the paper S is shown in FIG. As shown, it hits the guide member 293. At this time, the guide member 293 receives a pressing force in the curved inner direction from the leading edge of the paper S due to the stiffness of the paper S, and as a result, the compression spring 81 is compressed. The pressing force at this time is shown in FIG. If the surface of the guide member 293 slides in the direction toward the timing roller pair 24 immediately after the leading edge of the paper S hits the guide member 293, the pressing force is suddenly reduced. Therefore, since the displacement of the compression spring 81 in the compression direction is small, and the displacement of the guide member 293 in the curved inner direction is also small, the guide member 293 does not prevent proper guidance of the sheet S to the timing roller pair 24.

  Further, when the leading edge of the paper S starts to slide on the surface of the guide member 293 and the pressing force is suddenly weakened, the guide member 293 is pushed back to the position indicated by the broken line in FIG. As a result, the leading end portion of the sheet S is pushed back in the inner direction (outward direction of the curve) of the conveyance path, and the sheet S is more reliably guided to the timing roller pair 24. The compression spring 81 is a spring having an elastic coefficient such that the amount of compression when the leading edge of the sheet S hits does not hinder proper conveyance of the sheet S to the timing roller pair 24.

  Further, if the guide member 293 can be retracted to some extent inward of the curve from the guide position shown in FIG. 7, it is considered that the pushing force from the paper S can be absorbed and the knocking sound can be suppressed to some extent. The elastic coefficient 81 is not limited to an elastic coefficient such that the guide member 293 moves backward to a position where the paper S becomes straight as shown in FIG.

As described above, according to the configuration of the present embodiment, it is possible to achieve both suppression of the knocking sound and appropriate paper conveyance using the compression spring 81. Further, since a power source such as the guide motor 72 is not used, operation noise and power consumption of the guide motor 72 are suppressed, and an inexpensive compression spring 81 is used in place of the guide motor 72 and the cam 71. Can contribute to down.
<Embodiment 3>
In the first and second embodiments, the configuration has been described in which the guide member 293 constituting the entire guide surface inside the curve moves to the retracted position in the cassette conveyance path from the cassette feeding section 220 to the timing roller pair 24. However, there are cases where the entire guide surface inside the curve does not hit the paper S when the loop is eliminated, and it is also possible to suppress the knocking sound by making only the part that hits the paper S movable. In the present embodiment, a configuration in which a part of the guide member on the inner side of the curve is movable and both the suppression of the hitting sound and the appropriate sheet conveyance will be described.

In addition, in order to avoid duplication of description, the same components as those in Embodiments 1 and 2 are denoted by the same reference numerals and description thereof is omitted.
10, 11, and 12 are diagrams illustrating a schematic configuration of the conveyance path 29 in the present embodiment. FIG. 10 illustrates a state in which a loop is formed on the sheet fed from the sheet feeding cassette 21. 11 shows a state when the loop of FIG. 10 is eliminated, and FIG. 12 shows a state where the leading edge of the paper fed from the manual feed tray 25 hits the guide member 293. 11 and 12, the positions of the guide member 296 and the compression spring 81 in FIG. 10 are indicated by broken lines.

The guide member 296 is a plate-like member made of sheet metal, resin, or the like, and has a shape that is curved in a direction protruding to the inside of the conveyance path 29. One end of the compression spring 81 is connected to the surface of the guide member 296 opposite to the conveyance path 29, and the other end of the compression spring 81 is connected to a fixing member 82 such as a frame of the printer 100 main body. It is fixed.
When the loop shown in FIG. 10 is formed and the loop shown in FIG. 11 is eliminated, the guide member 296 receives a pressing force in the curved inner direction from the paper. Then, the compression spring 81 is compressed by the pressing force, and the guide member 296 moves inward of the curve and moves to the retracted position shown in FIG. At this time, since the pressing force is absorbed by the compression spring 81, the force with which the paper strikes the guide member 296 is weakened, and as a result, the beating sound is suppressed. When the trailing edge of the sheet passes through the cassette feeding unit 220 (the nip portion between the feeding roller 22 and the separating roller 26), the pressing force disappears, and the guide member 293 is moved to the position shown in FIG. Is returned to.

  When the paper S is fed from the manual feed tray 25, when the paper S sent from the manual feed unit 270 into the transport path 29 is transported to the timing roller pair 24, the leading edge of the paper S is shown in FIG. As shown in FIG. At this time, the guide member 296 receives a pressing force in the curved inner direction from the leading edge of the paper S due to the stiffness of the paper S, and as a result, the compression spring 81 is compressed. The pressing force at this time is shown in FIG. If the surface of the guide member 296 slides in the direction toward the timing roller pair 24 immediately after the leading edge of the paper S hits the guide member 296, the pressing force is smaller than the pressing force in the case shown. Therefore, since the displacement of the compression spring 81 in the compression direction is small, and the displacement of the guide member 296 in the curved inner direction is also small, proper guide of the sheet S to the timing roller pair 24 by the guide member 296 is hindered. Absent.

  When the leading edge of the sheet S begins to slide on the surface of the guide member 296 and the pressing force is suddenly weakened, the guide member 296 is pushed back to the position indicated by the broken line in FIG. As a result, the leading end portion of the sheet S is pushed back in the inner direction (outward direction of the curve) of the conveyance path, and the sheet S is more reliably guided to the timing roller pair 24. The compression spring 81 is a spring having an elastic coefficient such that the amount of compression when the leading edge of the sheet S hits does not hinder proper conveyance of the sheet S to the timing roller pair 24.

  Further, if the guide member 296 can be retracted to some extent inward of the curve from the guide position shown in FIG. 10, it is considered that the pushing force from the paper S can be absorbed and the knocking sound can be suppressed to some extent. The elastic coefficient 81 is not limited to an elastic coefficient such that the guide member 296 moves backward to a position where the paper S becomes straight as shown in FIG.

As described above, according to the configuration of the present embodiment, it is possible to achieve both suppression of the knocking sound and appropriate paper conveyance using the compression spring 81. Similarly to the second embodiment, since a power source such as the guide motor 72 is not used, the operation sound and power consumption of the guide motor 72 are suppressed, and an inexpensive compression spring is used instead of the guide motor 72 and the cam 71. Since 81 is used, it can contribute to cost reduction. Further, in the present embodiment, the guide member is movable only for the portion that contacts the loop portion of the paper S when the loop of the paper S is eliminated, so that the space for allowing the displacement of the guide member 296 is allowed. As a result, the apparatus can be reduced in size and weight.
<Modification>
As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and the following modifications can be considered.

  (1) In the first embodiment, when a print job is completed, before the next print job is started, the cam 71 is in the distant position and the guide member 293 is in the retracted position in advance. When the paper S used in the next print job is fed from the manual feed tray 25, the cam 71 is rotated to the close position and the guide member 293 is moved to the guide position. However, the present invention may be as follows. That is, before the next print job is started when the print job is completed, the cam 71 is positioned in the proximity position and the guide member 293 is positioned at the guide position, and used in the next print job. When the sheet S to be fed is fed from the paper feed cassette 21, the cam 71 may be rotated to the distant position and the guide member 293 may be moved to the retracted position.

FIG. 13 shows a flowchart showing the content of the guide member position control process in this modification.
First, when a print job is received (step S11: YES), it is determined whether or not it is the manual feed tray 25 that contains the paper S to be used for the next print job. If it is not the manual feed tray, the guide motor 72 is driven to rotate, the cam 71 is rotated to the distant position, the guide member 293 is moved to the retracted position, and then the print job is executed (step S12: NO, step S13, step S14).

If it is a manual feed tray, a print job is executed (step S12: YES, step S14).
Subsequently, it is determined whether or not the print job is completed. If the print job has not ended, the print job is continuously executed (step S15: NO, step S14). If the print job has been completed, it is next determined whether or not the cam 71 is in the proximity position (step S15: YES, step S16).

If the cam 71 is not in the proximity position, the guide motor 72 is driven to rotate, the cam 71 is rotated to the proximity position, the guide member 293 is moved to the guide position (step S16: NO, step S17), and the process returns to the main routine. To do. If the cam 71 is in the proximity position (step S16: YES), the process returns to the main routine.
As described above, when paper is fed from the paper feed cassette 21 at the time of executing the print job, the guide member 293 is moved to the retracted position to suppress the generation of the beating sound, and the paper is fed from the manual feed tray 25. In the case where the paper is fed from the manual feed tray 25, the guide member 293 is moved to the guide position to suppress the generation of a knocking sound when fed from the paper feed cassette 21. Paper conveyance can be performed appropriately.

(2) In the first embodiment and the modification example (1), the configuration using the cam mechanism as the moving unit 70 has been described, but the configuration is not limited thereto. For example, a solenoid may be used instead of the cam mechanism.
(3) In the above embodiments, the cassette conveyance path from the paper feed cassette 21 and the manual conveyance path from the manual feed tray 25 have been described as examples. However, the present invention is not limited to this. For example, in a printer configured to include a paper feed unit on the side surface of the printer body, in the case of a model capable of duplex printing, a transport path for the second side may be provided in the paper feed unit. In this case, the conveyance path for the first surface and the conveyance path for the second surface may have a shape that joins while curving while facing each other as in the above-described embodiments. Even in such a case, by applying the configurations of the cassette conveyance path and the manual conveyance path in each of the above-described embodiments and modifications to the conveyance path for the first surface and the conveyance surface for the second surface, respectively, it is possible to similarly suppress the knocking sound And appropriate paper conveyance.

(4) In the first embodiment and the modification example (1), the cam 71 is an eccentric cam having an elliptical cross section by a plane orthogonal to the axis, but is not limited to this. Alternatively, an eccentric cam having a circular cross section and a polygonal shape or the like may be used for the cross section.
(5) In the first embodiment and the modification example (1), when the guide member 293 is at the retracted position, the cam 71 contacts the guide member 293 at the farthest portion 711, and the guide member 293 is at the guide position. At this time, the cam 71 is in contact with the guide member 293 at the nearest portion 712. However, the present invention is not limited to this. If the guide member 293 is located at the retracted position and the guide position, You may contact | abut to the guide member 293 in any location.

  (6) In each of the above embodiments and modifications, a loop is formed on the paper in the conveyance path between the cassette feeding units 220 and 270 and the timing roller pair 24. However, the present invention is not limited to this. When an intermediate roller is provided in the conveyance path from the paper feed port to the timing roller pair, the curved shape such as between the intermediate roller and the timing roller pair or between the paper feed port and the intermediate roller is used. A loop may be formed in the conveyance path. In this case, the conveyance means on the upstream side in the sheet conveyance direction in the conveyance path of the part where the loop is formed is not necessarily a conveyance composed of a combination of a feeding roller and a separation roller like the cassette feeding unit 220 and the manual feeding unit 270. It may not be a means. For example, instead of the rolling roller, a rotating body such as a roller or a belt that rotates in a direction that rotates with the feeding roller may be used.

  (7) In each of the above-described embodiments and modifications, the leading edge of the sheet S is abutted against the stopped timing roller pair 24 and is further fed to form a loop on the sheet S, and then the timing is reached. Although the rotation of the roller pair 24 starts and the loop is eliminated, the present invention is not limited to this. For example, a loop is formed in the paper because the peripheral speed of the upstream roller in the paper transport direction is slower than the peripheral speed of the downstream roller, and then the peripheral speed of the upstream roller is higher than the peripheral speed of the downstream roller. The loop may be eliminated by increasing the speed.

(8) The guide member 296 in Embodiment 3 is not limited to a curved plate-like member, and a member having a roller or cam shape may be used.
(9) In each of the above embodiments and modifications, a stopper that stops the displacement of the guide members 293 and 296 may be provided so that the guide members 293 and 296 stop at the retracted position and the guide position. In this case, it is preferable to provide a shock absorbing material such as sponge or rubber on the surface of the stopper that comes into contact with the guide members 293 and 296 so as to suppress an impact sound at the time of contact.

  (10) In the first embodiment and the modification example (1), the guide member 293 receives the force due to its own weight in the direction of moving from the retracted position to the guide position, but is not limited thereto. For example, it may be biased by an elastic member such as a compression spring or a tension spring in the direction of moving from the retracted position to the guide position. Further, it may be biased by an elastic member in the direction of moving from the guide position to the retracted position. In this case, the cam 71 is disposed so as to abut on the surface opposite to the conveyance path of the guide member 293, and the abutment position is not limited to the outside of the sheet conveyance area, and hinders the biasing by the elastic member. As long as the position does not exist, the guide member 293 may contact at any position on the surface opposite to the conveyance path.

  (11) In the second and third embodiments, the guide members 293 and 296 are urged by the compression spring 81 in the direction of moving from the retracted position to the guide position. However, the present invention is not limited to this. . For example, it may be biased by a tension spring in the above direction. In this case, a tension spring is disposed on the conveyance path side of the guide members 293 and 296, but it is desirable that the urging position is outside the sheet conveyance area so as not to disturb the sheet conveyance. Moreover, it is not restricted to a compression spring or a tension spring, You may use elastic members, such as rubber | gum.

  (12) In each of the above-described embodiments and modifications, the guide member in the curved inner portion of the cassette conveyance path 29a is displaceable, and the guide member in the curved inner portion of the manual feed path 29b is not displaced. However, the present invention is not limited to this. For example, the guide member in the curved inner portion of the manual feed path 29b can be displaced and the guide member in the curved inner portion of the manual feed path 29b may not be displaced. Also, the cassette carrying path 29a and the manual feed path may be arranged. The configuration may be such that the guide members of the inner portions of both of the curves 29b can be displaced. In these cases, in the curved portion (another curved portion) of the manual feed path 29b that is the third transport path, the second guide member (another inner guide member) in the inner portion of the curve is removed from the paper feed cassette 21. A state in which the sheet S is straight between the position (third position) where the sheet S delivered by the cassette feeding unit 220 is smoothly guided to the timing roller pair and the manual feeding unit 270 and the timing roller pair 24. It is preferable that the sheet S is supported so as to be displaceable from a position (fourth position) retracted inward of the curve from the position of the sheet S when being conveyed. Furthermore, the second guide member may be urged in a direction to be displaced from the fourth position to the third position by the second elastic member (another elastic member). In addition, as a mechanism for displacing the second guide member to the third position and the fourth position, a second guide displacement mechanism (another guide displacement mechanism) including a moving means such as a cam or a solenoid is provided. Alternatively, the guide displacement mechanism including the moving unit 70 may also serve as the second displacement mechanism to move both the guide member 293 and the second guide member.

(13) In each of the above embodiments and modifications, the conveyance path has a curved shape. However, the present invention is not limited to this, and a curved shape may be used.
(14) Although the sheet conveying apparatus according to the present invention has been described by taking a tandem type color digital printer as an example, the present invention is not limited to a tandem type color digital printer, and is a monochrome / color copier, printer, fax machine. In addition, the present invention is applied to all image forming apparatuses having a sheet conveying apparatus, such as a multifunction peripheral (MFP) having these functions.

  (15) In each of the above-described embodiments and modifications, the paper conveyance path in the image forming apparatus has been described as an example. However, the present invention is not limited to this. For example, in an image reading apparatus equipped with an automatic document feeder (ADF), when a document is transported to a reading position, it is used to correct a skew in a portion having a curved shape in the document transport path. The present invention can also be applied when a loop is formed.

  Further, the contents of the above embodiments and the above modifications may be combined.

  INDUSTRIAL APPLICABILITY The present invention is useful as a technique for reducing user discomfort with respect to an impact sound generated due to a sheet during sheet conveyance in an image forming apparatus.

DESCRIPTION OF SYMBOLS 10 Image forming part 20 Paper feed part 21 Paper feed cassette 22, 27 Feed roller 23, 29 Conveyance path 24 Timing roller pair 25 Manual feed tray 26, 28 Rolling roller 29a Cassette conveyance path 29b Manual feed path 30 Transfer part 31 Intermediate transfer belt 32 Driving roller 35 Secondary transfer roller 36 Secondary transfer position 40 Fixing device 70 Moving portion 71 Cam 72 Guide motor 73 Rotating shaft 81 Compression spring 82 Fixed member 100, 200 Printer 220 Cassette feeding portions 231, 232, 291, 292, 293 296 Guide member 270 Manual feed portion 294 Swing support portion 295 Support shaft 711 Farthest portion 712 Nearest portion

Claims (9)

Each of the first conveying means that conveys the sheet by a pair of rotating bodies, one rotating body, and one pressing member that is pressed by the rotating body, each of which selectively selects the sheet up to the first conveying means. A sheet conveying apparatus having a configuration in which a loop is temporarily formed on the sheet between the first conveying means and the second conveying means in the middle of conveyance. ,
A position where the loop of the first conveyance path from the second conveyance means to the first conveyance means is formed is a curved portion bent in a direction protruding to one side, and the formation of the loop Includes a curved part bent in the direction in which the sheet bends ,
The second conveyance path from the third conveyance means to the first conveyance means is joined to the first conveyance path from the protruding side of the curved portion in the curved portion;
Of the guide members forming the first conveyance path, the inner guide member including the inner portion of the curved portion guides the sheet conveyed by the third conveyance means to the first conveyance means. A sheet displacement mechanism is provided that supports a displacement at a position of 1 and a second position that is a position retracted inward of the curved portion from the first position. apparatus. When the sheet is conveyed from the third conveying unit, the guide displacement mechanism moves the inner guide member to the first position, and when the sheet is conveyed from the second conveying unit. The sheet conveying apparatus according to claim 1, further comprising a moving unit that moves the second position. The sheet conveying apparatus according to claim 1, wherein the inner guide member is pivotally supported by the apparatus main body frame so as to be displaceable between the first position and the second position. The guide displacement mechanism includes an elastic member,
The said inner side guide member is urged | biased in the direction displaced from the said 2nd position to the said 1st position by the said elastic member. The Claim 1 characterized by the above-mentioned. Sheet conveying device. In the course of conveyance, the sheet further includes a configuration for temporarily forming a loop between the first conveyance unit and the third conveyance unit,
The second conveyance path includes another curved portion bent in a direction protruding toward the first curved portion,
Of the guide members forming the second conveyance path, another inner guide member including an inner portion of the another curved portion is used, and the sheet conveyed by the second conveyance unit is transferred to the first conveyance unit. There is provided another guide displacement mechanism that supports the first position and the fourth position, which is a position retracted from the third position toward the inner side of the other curved portion so as to be displaceable. The sheet conveying device according to any one of claims 1 to 4, wherein the sheet conveying device is characterized in that: When the sheet is conveyed from the second conveying unit, the another guide displacement mechanism moves the other inner guide member to the third position and conveys the sheet from the third conveying unit. In the case, the sheet conveying apparatus according to claim 5, further comprising another moving unit that moves to the fourth position. The sheet conveying apparatus according to claim 5 or 6, wherein the another inner guide member is pivotally supported by the apparatus main body frame so as to be displaceable between the third position and the fourth position. The another guide displacement mechanism includes another elastic member,
The said another inner guide member is urged | biased by the direction which displaces from the said 4th position to the said 3rd position by the said another elastic member. The any one of Claim 5 to 7 characterized by the above-mentioned. The sheet conveying apparatus according to item.   An image forming apparatus comprising the sheet conveying device according to claim 1.

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